Description: Some 30,000 species of spiders occur throughout the world. They have eight legs and two body segments. For the most part, they are considered to be beneficial because they feed primarily on insect pests and other spiders. At times they become a nuisance by finding their way into our homes. This typically occurs in the early fall when cooler temperatures force them to seek shelter. Many people become extremely upset by their mere presence of spiders and have a very low tolerance level for any sort of “creepy crawly.”
Almost all spiders are harmless and usually remain hidden. They do not seek out and bite humans. In fact, most cannot penetrate our skin with their fangs. A few are considered venomous to humans and care must be taken to avoid being bitten. Potentially dangerous spiders include:
Black Widow (Latrodectus spp.) – Adults have shiny black bodies (9/16 inch long) with a distinctive red or red-orange shaped hourglass pattern on the underside of the abdomen. They are not aggressive and often found in dark, undisturbed areas including window wells, crawl spaces, corners of garages, and old rodent burrows. Their bite is rarely fatal.
Brown Recluse (Loxoceles reclusa) – Pale brown or buckskin colored, these venomous spiders (1/3 inch long) have long, dark brown legs and a violin shaped darker marking on the top of the body near the head. They are not aggressive and live within a loose web in dark corners of buildings. Their bite is painful, often leaving an ulcerous wound, but is rarely fatal.
Hobo Spider (Tegenaria agrestis) – Originally from Europe, hobo spiders ended up in Seattle, Washington sometime before the 1930′s. Since then they have slowly expanded throughout the Northwestern United States and Western Canada. Adults (1/4 inch long) are brown in color and have a chevron pattern on their abdomen. They live in a funnel web and are often found between bricks, in crawl spaces, around out buildings, and under wood. More aggressive than most, their bite is similar to that of the brown recluse and is rarely fatal.
Note: There are a large number of non-poisonous spiders across North America that are similar in description to the hobo spider. As a result, many other species should suspected before even considering the hobo spider as a possibility.
Life Cycle: The life-cycle varies greatly depending upon species. In most cases, females reproduce by laying eggs in a silken egg sac. The egg sac is either carried around or hidden in the web. Tiny, newly hatched spiders emerge 2-3 weeks later. Most mature to adults in about one year. Several species live 1-2 seasons, but the females of a few species may live 5-20 years. Males and females live separately and only come together to mate.
Spider Control: Discourage through good housekeeping, both inside and out. Keep boxes, old equipment, and other items neatly stored on shelves, particularly in garages and basements; clean up and dispose of trash, debris, old equipment, etc. Repair screens and maintain the weather-stripping around doors and windows. Apply Tanglefoot Pest Barrier to incoming pipes and door jambs to intercept these pests. Inside the house, spiders and their webs can be eliminated by using a broom or vacuum cleaner. Traps placed into small, tight corners will capture many crawling insects. If pest populations become intolerable, apply diatomaceous earth and/or botanical insecticides to cracks, crevices and other hiding places. For crawl spaces consider using a least-toxic insect fogger.
Photo Credit: Chad and Stacey Hall